To minimize the treatment risk, participants in the trial will be staged according to location of the disease in the prostate. The first 3 participants recruited to the trial will have targeted loci well separated from the urethra, erectile nerves and the rectum, and so treatment in this region poses minimal risk of injury to these vital structures. Lesions sizes measured in this initial stage will be used in planning fiber placement in the three remaining stages, in which fiber placement is closer to critical structures such as the urethra (Stage 2), erectile nerves (Stage 3) and rectum (Stage 4).